1. Field
The present invention relates to an energy storage device (system).
2. Description of the Related Art
To solve waste due to power oversupply and overload due to a power supply shortage as well as to effectively overcome a mismatch between power production and consumption, a smart grid system has been researched to flexibly control the amount of power supply in connection with various information and communication technologies.
That is, the smart grid system includes an energy storage system that stores power when the power consumption is low and supplies the stored power along with produced power to consumers when the power consumption is high.
In order to store the produced power, the energy storage system includes battery packs that include rechargeable batteries.
The energy storage system can be used not only in the smart grid system but also in an electric vehicle charging station for supplying the charged power to electric vehicles.
As an example, the energy storage system may be configured by installing a plurality of battery packs in a rack and then placing a plurality of racks in a container.
Each battery pack is formed by collecting and electrically connecting a plurality of rechargeable batteries in various suitable structures.
Each rechargeable battery generates heat since it repeatedly performs charging and discharging operations due to its internal electrochemical reaction.
Accordingly, as rechargeable batteries having high capacity are developed and their corresponding battery packs are highly concentrated, a corresponding energy storage system generates an excessively large amount of heat due to the charging and discharging operations of the rechargeable batteries.
Such heat generation may cause internal damage to the rechargeable batteries, thereby degrading the performance and lifespan of the rechargeable batteries.
In order to prevent this, an air conditioning system is used to cool the rechargeable batteries and the battery packs.
As an example, in an up-flow system, a cooling air current is changed to a warm air current after cooling the battery pack, and the warm air current and a newly supplied cooling air current are mixed in the middle by convection.
Thus, a cooling effect for the battery pack is reduced.
That is, large temperature deviations (or variations) occur between a region to which the cooling air current is directly supplied and regions to which the warm air current is supplied or the mixed air current is supplied.
In such up-flow and down-flow systems, the temperature deviations (or variations) increase at an overall region inside the container and between the battery packs in one rack.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.